Endovascular prosthesis and delivery device

ABSTRACT

In one of its aspects, the present invention relates to an endovascular prosthesis. The endovascular prosthesis comprises a first expandable portion expandable from a first, unexpanded state to a second, expanded state to urge the first expandable portion against a vascular lumen and a retractable leaf portion attached to the first expandable portion. The retractable leaf portion comprises at least one spine portion and a plurality of rib portions attached to the spine portion. Longitudinally adjacent pairs of rib portions are free of interconnecting struts. The endovascular prosthesis that can be unsheathed and re-sheathed for repositioning of the endovascular prosthesis prior to final deployment thereof. There is also described a delivery device that that is particularly well suited to delivering the present endovascular prosthesis through tortuous vasculature in the body.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 14/065,788, filed Oct. 29, 2013, which is a continuation ofInternational Application No. PCT/CA2012/000379, which was published inEnglish and designated the U.S., which claims benefit of provisionalU.S. Patent Appln. No. 61/457,604 and provisional U.S. Patent Appln. No.61/457,605, each filed Apr. 29, 2011, the contents of all incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

In one of its aspects, the present invention relates to an endovascularprosthesis. In another of its aspects, the present invention relates toa method of treating an aneurysm in a patient. In another of itsaspects, the present invention relates to an endovascular prosthesisdelivery device. Other aspects of the invention will be apparent tothose of skill in the art having in hand the present specification.

2. Description of the Prior Art

As is known in the art, an aneurysm is an abnormal bulging outward inthe wall of an artery. In some cases, the bulging may be in the form ofa smooth bulge outward in all directions from the artery—this is knownas a “fusiform aneurysm”. In other cases, the bulging may be in the formof a sac arising from an arterial branching point or from one side ofthe artery—this is known as a “saccular aneurysm”.

While aneurysms can occur in any artery of the body, it is usually thosewhich occur in the brain which lead to the occurrence of a stroke. Mostsaccular aneurysms which occur in the brain have a neck which extendsfrom the cerebral blood vessel and broadens into a pouch which projectsaway from the vessel.

The problems caused by such aneurysms can occur in several differentways. For example, if the aneurysm ruptures, blood enters the brain orthe subarachnoid space (i.e., the space closely surrounding thebrain)—the latter is known as an aneurysmal subarachnoid hemorrhage.This is followed by one or more of the following symptoms: nausea,vomiting, double vision, neck stiffness and loss of consciousness.Aneurysmal subarachnoid hemorrhage is an emergency medical conditionrequiring immediate treatment. Indeed, 10-15% of patients with thecondition die before reaching the hospital for treatment. More than 50%of patients with the condition will die within the first thirty daysafter the hemorrhage. Of those patients who survive, approximately halfwill suffer a permanent stroke. Some of these strokes occur one to twoweeks after the hemorrhage itself from vasospasm in cerebral vesselsinduced by the subarachnoid hemorrhage. Aneurysms also can causeproblems which are not related to bleeding although this is less common.For example, an aneurysm can form a blood clot within itself which canbreak away from the aneurysm and be carried downstream where it has thepotential to obstruct an arterial branch causing a stroke (e.g., anischemic stroke). Further, the aneurysm can also press against nerves(this has the potential of resulting in paralysis or abnormal sensationof one eye or of the face) or the adjacent brain (this has the potentialof resulting in seizures).

Given the potentially fatal consequences of the aneurysms, particularlybrain aneurysms, the art has addressed treatment of aneurysms usingvarious approaches.

Generally, aneurysms may be treated from outside the blood vessels usingsurgical techniques or from the inside using endovascular techniques(the latter falls under the broad heading of interventional (i.e.,non-surgical) techniques).

Surgical techniques usually involve a craniotomy requiring creation ofan opening in the skull of the patient through which the surgeon caninsert instruments to operate directly on the brain. In one approach,the brain is retracted to expose the vessels from which the aneurysmarises and then the surgeon places a clip across the neck of theaneurysm thereby preventing arterial blood from entering the aneurysm.If there is a clot in the aneurysm, the clip also prevents the clot fromentering the artery and obviates the occurrence of a stroke. Uponcorrect placement of the clip the aneurysm will be obliterated in amatter of minutes. Surgical techniques are the most common treatment foraneurysms. Unfortunately, surgical techniques for treating theseconditions are regarded as major surgery involving high risk to thepatient and necessitate that the patient have strength even to have achance to survive the procedure.

As discussed above, endovascular techniques are non-surgical techniquesand are typically performed in an angiography suite using a catheterdelivery system. Specifically, known endovascular techniques involveusing the catheter delivery system to pack the aneurysm with a materialwhich prevents arterial blood from entering the aneurysm—this techniqueis broadly known as embolization. One example of such an approach is theGuglielmi Detachable Coil which involves intra-aneurysmal occlusion ofthe aneurysm via a system which utilizes a platinum coil attached to astainless steel delivery wire and electrolytic detachment. Thus, oncethe platinum coil has been placed in the aneurysm, it is detached fromthe stainless steel delivery wire by electrolytic dissolution.Specifically, the patient's blood and the saline infusate act as theconductive solutions. The anode is the stainless steel delivery wire andthe cathode is the ground needle which is placed in the patient's groin.Once current is transmitted through the stainless steel delivery wire,electrolytic dissolution will occur in the uninsulated section of thestainless steel detachment zone just proximal to the platinum coil (theplatinum coil is of course unaffected by electrolysis). Other approachesinvolve the use of materials such as cellulose acetate polymer to fillthe aneurysm sac. While these endovascular approaches are an advance inthe art, they are disadvantageous. Specifically, the risks of theseendovascular approaches include rupturing the aneurysm during theprocedure or causing a stroke (e.g., an ischemic stroke) due to distalembolization of the device or clot from the aneurysm. Additionally,concern exists regarding the long term results of endovascular aneurysmobliteration using these techniques. Specifically, there is evidence ofintra-aneurysmal rearrangement of the packing material and reappearanceof the aneurysm on follow-up angiography.

One particular type of brain aneurysm which has proven to be verydifficult to treat, particularly using the surgical clipping orendovascular embolization techniques discussed above occurs at thedistal basilar artery. This type of aneurysm is a weak outpouching,usually located at the terminal bifurcation of the basilar artery.Successful treatment of this type of aneurysm is very difficult due, atleast in part, to the imperative requirement that all the brainstemperforating vessels be spared during surgical clip placement.

Unfortunately, there are occasions when the size, shape and/or locationof an aneurysm make both surgical clipping and endovascular embolizationnot possible for a particular patient. Generally, the prognosis for suchpatients is not good.

Accordingly, while the prior art has made advances in the area oftreatment of aneurysms, there is still room for improvement,particularly in endovascular embolization since it is such an attractivealternative to major surgery.

In International Publication Number WO 99/40873 [Marotta et al.(Marotta)], published Aug. 19, 1999, there is taught a novelendovascular approach useful in blocking of an aneurysmal opening,particularly those in saccular aneurysms, leading to obliteration of theaneurysm. The approach is truly endovascular in that, with theendovascular prosthesis taught by Marotta, there is no requirement topack the aneurysmal sac with a material (e.g., such is used with theGuglielmi Detachable Coil). Rather, the endovascular prosthesis taughtby Marotta operates on the basis that it serves to block the opening tothe aneurysmal sac thereby obviating the need for packing material.Thus, the endovascular prosthesis taught by Marotta is an importantadvance in the art since it obviates or mitigates many of thedisadvantages of the prior art. The endovascular prosthesis taught byMarotta comprises a leaf portion capable of being urged against theopening of the aneurysm thereby closing the aneurysm. In theendovascular prosthesis taught by Marotta, the leaf portion is attachedto, and independently moveable with respect to, a body comprising atleast one expandable portion. The expandable portion is expandable froma first, unexpanded state to a second, expanded state with a radiallyoutward force thereon. Thus, the body serves the general purpose offixing the endovascular prosthesis in place at a target body passagewayor vascular lumen in the vicinity at which the aneurysmal opening islocated and the leaf portion serves the purpose of sealing theaneurysmal opening thereby leading to obliteration of the aneurysm.Thus, as taught by Marotta, the leaf portion functions and movesindependently of the body of the endovascular prosthesis.

While the endovascular prosthesis taught by Marotta is a significantadvance in the art, there is still room for improvement. Specifically,in the preferred embodiment of the endovascular prosthesis taught byMarotta, once the device is partially or fully deployed, for all intentsand purposes, it is not possible to retrieve the prosthesis—e.g., forre-positioning. While this may not be a problem in most instances, thereare occasions where the physician wishes to be able to retrieve thedevice so that it may be repositioned for optimum placement.

Accordingly, there remains a need in the art for an endovascularprosthesis that may be retrieved by the physician after it has beenpartially or fully deployed. It would be particularly advantageous tohave a self-expanding endovascular prosthesis that may be retrieved bythe physician after it has been partially or fully deployed.

SUMMARY OF THE INVENTION

It is an object of the present invention to obviate or mitigate at leastone of the above-mentioned disadvantages of the prior art.

It is another object of the present invention to provide a novelendovascular prosthesis.

It is another object of the present invention to provide a novelendovascular prosthesis delivery device.

Accordingly, in one of its aspects, the present invention provides anendovascular prosthesis comprising

a first expandable portion expandable from a first, unexpanded state toa second, expanded state to urge the first expandable portion against avascular lumen; and

a retractable leaf portion attached to the first expandable portion, theretractable leaf portion comprising at least one spine portion and aplurality of rib portions attached to the spine portion, longitudinallyadjacent pairs of rib portions being free of interconnecting struts.

In another of its aspects, the present invention provides anendovascular prosthesis delivery device comprising a tubular memberhaving a distal portion and a proximal portion, the distal portionhaving a porous surface defined by a plurality of circumferential rings,adjacent pairs of circumferential rings being interconnected by at leastone longitudinal strut, the porous surface comprising a decreasinggradient of longitudinal strut circumferential width betweenlongitudinal struts connected to opposed sides of a singlecircumferential ring in a direction from the proximal portion to thedistal portion.

In another of its aspects, the present invention provides anendovascular prosthesis delivery device comprising a tubular memberhaving a distal portion and a proximal portion, the distal portionhaving a porous surface defined by a plurality of circumferential rings,adjacent pairs of circumferential rings being interconnected by at leastone longitudinal strut, the porous surface comprising a increasingporosity in a direction from the proximal portion to the distal portion.

In a preferred embodiment, the porous surface of the delivery devicecomprises a cover layer, preferably made of a polymer and/or preferablydisposed substantially continuously over the porous surface, to reducefriction between the delivery device and the inner surface of a deliverycatheter, facilitating a low force delivery of the endovascularprosthesis. The nature of the cover layer will be described in moredetail hereinbelow.

Thus, the present inventors have discovered a novel endovascularprosthesis that can be unsheathed and re-sheathed for repositioning ofthe endovascular prosthesis prior to final deployment thereof. Thisprovides the clinician with a significant advantage over the prior artdevices described above. The present endovascular prosthesis comprises afirst expandable portion expandable from a first, unexpanded state to asecond, expanded state to urge the first expandable portion against thewall of the vascular lumen such as an artery. The endovascularprosthesis further comprises a retractable leaf portion attached to thefirst expandable portion; the retractable leaf portion serves tofacilitate stasis and thrombotic occlusion of the aneurysm. Theretractable leaf portion comprises at least one spine portion and aplurality of rib portions attached to the spine portion. Importantly,longitudinally adjacent pairs of rib portions are free of intricateconnecting struts. The present inventors conducted a number of tests andhave discovered that when connections are made between adjacent ribportions, the retractability of the leaf portion is significantlycompromised and, in many cases, the leaf portion may not be retracted atall.

In addition, the present endovascular prosthesis is advantageous in thatit has a natural tendency to flex in a manner such that the spineportion is on the outside of the bend. This is highly advantageous,especially when the device is implanted in a bifurcated body passageway.An additional advantage is that the orientation of the rib portions,coupled with the flex, particularly facilitates atraumatic and accuratedelivery and deployment of the present endovascular prosthesis.

While not wishing to be bound by any particular theory or mode ofaction, it has been found that the rib portions of the presentendovascular prosthesis are compressible whereas the spine in notcompressible; therefore under an axial loading in the sheath, the ribportions have a tendency to compress and induce a bend that facilitatesproper orientation during delivery in the correct direction.

In a highly advantageous embodiment, the present endovascular prosthesisis configured to be self-expanding. This means that the device may besheathed or otherwise restrained prior to deployment and after initialdelivery of the device, the sheath or restraint is partially retractedthereby allowing the device to self-expand. This allows for partial andprogressive deployment of the device with the advantage that theclinician can re-sheath the device if initial deployment of theendovascular prosthesis is not in the correct position with respect tothe target anatomy of the patient. In this context, it is also possibleto achieve an additional rotational orientation of the presentendovascular prosthesis by delivering the prosthesis using a ‘torquablecatheter’. This involves partially deploying the prosthesis to evaluaterotational orientation. If the rotation of the device relative to theaneurysm neck needs to be adjusted, the prosthesis may be retracted intothe torquable catheter, torqued into the another orientation and thenthese steps are repeated until the prosthesis is deemed to be in thecorrect position relative to the aneurysm neck, after which theprosthesis may be fully unsheathed and detached from the delivery deviceusing a number of techniques such as those described in more detailbelow. This is another highly advantageous feature of the presentendovascular prosthesis.

Another aspect of the present invention relates to the provision of anendovascular prosthesis delivery device which comprises the tubularmember having a distal portion and a proximal portion. The distalportion of the endovascular prosthesis has a porous surface made up ofthe number of circumferential rings with adjacent pairs of these ringsbeing interconnected by one or more longitudinal struts. The poroussurface in the distal portion of the endovascular prosthesis deliverydevice has a decrease in the width between a pair of the longitudinalstruts connected to opposed sides of a given circumferential ring. Thisdecrease in circumferential width of longitudinal strut runs in adirection from the proximal portion of the tubular member to the distalportion of the tubular member. Consequently, this means that the distalportion of the tubular member becomes progressively more flexible in adirection toward the distal most end of the tubular member. This featurefacilitates navigating the endovascular prosthesis delivery devicethrough tortuous anatomy while providing sufficient integrity and radialrigidity at the user end of the tubular member to be able to insert thedevice in the patient and navigate it completely to the target anatomyall the while obviating or mitigating kinking of the endovascularprosthesis delivery device. In a preferred embodiment, there is adecrease in the circumferential width between pairs of thecircumferential rings running in a direction from proximal portion tothe distal portion.

In a particularly preferred embodiment of the present endovascularprosthesis delivery device, the circumferential rings comprise a seriesof alternating peaks and valleys. In this preferred embodiment, it isfurther preferred that the longitudinal struts connect a valley from onecircumferential ring with a valley in an adjacent circumferential ring.This so-called valley-valley connection embodiment is characterized byhaving the peaks in adjacent circumferential rings longitudinallyaligned but unconnected. The advantage of this approach is that when theendovascular prosthesis delivery device is flexed to a certain degree,the adjacent peaks will contact each other prior to the endovascularprosthesis delivery device kinking, bending too much andyielding/breaking.

The present endovascular prosthesis is believed to be particularlyuseful in the treatment of aneurysms such as those described hereinaboveand is therefore believed to provide a significant alternative to theconventional surgical techniques described hereinabove. Additionally, itis envisaged that the present endovascular prosthesis may be used in thetreatment of certain aneurysms which are diagnosed as being inoperable.The present endovascular prosthesis also is believed to provide asignificant advantage of current endovascular approaches such as theGuglielmi Detachable Coil described hereinabove. Specifically, since thepresent endovascular prosthesis does not rely on insertion into theaneurysm of a metal packing material (e.g., platinum coil), the risk ofrupturing the aneurysm is mitigated as is the risk of intra-aneurysmalrearrangement of the metal packing material and subsequent reappearanceof the aneurysm. Of course, those of skill in the art will recognizethat there may be certain situations where the present endovascularprosthesis could be used in combination with Guglielmi Detachable Coilsdescribed hereinabove—e.g., to treat an aneurysm with a large neck inwhich an added structure across the neck (i.e., the present endovascularprosthesis) would help hold the coils with in the aneurysmal sac (thiswould obviate or mitigate the possibility of a coil exiting the aneurysmsac and causing an ischemic stroke).

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will be described with reference tothe accompanying drawings, wherein like reference numerals denote likeparts, and in which:

FIG. 1 illustrates a two-dimensional representation of a firstembodiment of the present endovascular prosthesis;

FIG. 1 a is an enlarged view of a portion of FIG. 1 identifying variouselements in the design of the prosthesis;

FIG. 2 illustrates a perspective view of the endovascular prosthesisillustrated in FIG. 1;

FIG. 3 illustrates a top view of the endovascular prosthesis illustratedin FIGS. 1-2 coupled to a delivery device;

FIG. 4 illustrates delivery of the endovascular prosthesis illustratedin FIGS. 1-3 to occlude an aneurysm;

FIGS. 5-6 illustrate a portion of the endovascular prosthesisillustrated, in a transparent sheath, in FIGS. 1-4 as it is reversiblysheathed and unsheathed;

FIG. 7 illustrates the endovascular prosthesis illustrated in FIGS. 1-6after it has been released from the delivery device and is in thecorrect position to treat the aneurysm;

FIG. 8 illustrates the endovascular prosthesis illustrated in FIGS. 1-7after it has been deployed and is occluding an aneurysm (also, thedelivery device is pulled away from the endovascular prosthesis);

FIG. 9 illustrates a two-dimensional representation of a secondembodiment of the present endovascular prosthesis;

FIG. 10 illustrates a perspective view of the endovascular prosthesisillustrated in FIG. 9;

FIG. 11 illustrates a perspective view of the endovascular prosthesisillustrated in FIGS. 9-10 coupled to a delivery device;

FIGS. 12( a)-12(c) illustrate details of how the endovascular prosthesisillustrated in FIGS. 9-11 is coupled to the delivery device;

FIG. 13 illustrates a two-dimensional representation of a thirdembodiment of the present endovascular prosthesis;

FIG. 14 illustrates a perspective view of the endovascular prosthesisillustrated in FIG. 13 as it is coupled to a delivery device;

FIGS. 15( a)-15(d) illustrate further detail of coupling of theendovascular prosthesis illustrated in FIGS. 13-14 to the deliverydevice;

FIG. 16 illustrates a two-dimensional representation of a fourthembodiment of the present endovascular prosthesis;

FIG. 17 illustrates a perspective view of the endovascular prosthesisillustrated in FIG. 16;

FIGS. 18( a)-18(f), and 9-21 illustrate, in a step-wise manner,deployment of the endovascular prosthesis illustrated in FIGS. 16-17 inan aneurysm located at the junction of a bifurcated artery;

FIGS. 22-24 illustrate, in a step-wise manner, release of one end of theendovascular prosthesis illustrated in FIGS. 16-21 from the deliverydevice;

FIG. 25 illustrates a perspective view of a portion of the deliverydevice used to deliver the endovascular prosthesis illustrated in FIGS.16-24;

FIGS. 26-27 illustrate an enlarged view of the portion of the deliverydevice illustrated in FIG. 25 and how it is coupled to an opposite end(cf. FIGS. 22-24) of the endovascular prosthesis illustrated in FIGS.16-24;

FIG. 28 illustrates a two-dimensional representation of a fifthembodiment of the present endovascular prosthesis;

FIG. 29 illustrates a perspective view of the endovascular prosthesisillustrated in FIG. 28;

FIGS. 30-32 illustrate, in a step-wise manner, release of theendovascular prosthesis illustrated in FIGS. 28-29 from its deliverydevice;

FIGS. 33-35 illustrate additional views of a delivery device used todeliver the endovascular prosthesis illustrated in FIGS. 28-32;

FIG. 36 illustrates a two-dimensional representation of a sixthembodiment of the present endovascular prosthesis;

FIG. 37 illustrates a perspective view of the endovascular prosthesisillustrated in FIG. 36 connected to a delivery device therefor;

FIGS. 38( i)-(iii) illustrate a portion of a preferred embodiment of thepresent endovascular prosthesis delivery device (including enlargedviews in FIGS. 38( a)-(d)); and

FIGS. 39( a)-39(d), 40(a)-40(d), 41, 42(a)-42(c), and 43(a)-43(e)illustrate various views of various endovascular prosthesis deliverydevices that are shown throughout FIGS. 1-37.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In one of its aspects, the present invention relates to an endovascularprosthesis comprising: a first expandable portion expandable from afirst, unexpanded state to a second, expanded state to urge the firstexpandable portion against a vascular lumen; and a retractable leafportion attached to the first expandable portion, the retractable leafportion comprising at least one spine portion and a plurality of ribportions attached to the spine portion, longitudinally adjacent pairs ofrib portions being free of interconnecting struts. Preferred embodimentsof this endovascular prosthesis may include any one or a combination ofany two or more of any of the following features:

-   -   a single spine portion is connected to the first expandable        portion;    -   the single spine portion comprises a row of rib portions        connected to one side of the single spine portion;    -   the single spine portion comprises a pair of rows of rib        portions, each row of rib portions connected to one side of the        single spine portion;    -   the single spine portion comprises a pair of rows of rib        portions connected to opposed sides of the single spine portion;    -   in two dimensions, each row of rib portions is a substantial        mirror image of an adjacent row of rib portions along the single        spine portion;    -   a first row of rib portions is connected at a plurality of first        connection points to the single spine portion and a second row        of rib portions is connected at a plurality of second connection        points to the single spine portion, the plurality of first        connection points and the plurality of second connection points        being longitudinally aligned with respect to one another;    -   a first row of rib portions is connected at a plurality of first        connection points to the single spine portion and a second row        of rib portions is connected at a plurality of second connection        points to the single spine portion, the plurality of first        connection points and the plurality of second connection points        being longitudinally staggered with respect to one another;    -   the single spine portion is linear;    -   the single spine portion is curvilinear;    -   the single spine portion is curved;    -   the single spine portion comprising an undulating pattern        comprising alternating peaks and valleys;    -   at least some rib portions are connected to the peaks in the        undulating pattern;    -   each rib portion is connected to a peak in the undulating        pattern;    -   in two dimensions, each rib portion is configured substantially        to form an acute angle with respect to a spine longitudinal axis        of the single spine portion;    -   in two dimensions, each rib portion comprises a rib proximal        portion, a rib distal portion and a rib intermediate portion        disposed therebetween;    -   in two dimensions, each rib portion has a substantially constant        circumferential width;    -   in two dimensions, each rib portion has a variable        circumferential width;    -   in two dimensions, the rib intermediate portion has a        circumferential width less than at least one of the rib proximal        portion and the rib distal portion;    -   the rib intermediate portion has a circumferential width less        than both of the rib proximal portion and the rib distal        portion;    -   the rib proximal portion has a circumferential width in the        range of from about 0.0010 to about 0.0120 inches;    -   the rib proximal portion has a circumferential width in the        range of from about 0.0017 to about 0.0096 inches;    -   the rib proximal portion has a circumferential width in the        range of from about 0.0024 to about 0.0072 inches;    -   the rib proximal portion is from about 1% to about 10% of the        overall length of the rib portion;    -   the rib proximal portion is from about 2% to about 6% of the        overall length of the rib portion;    -   the rib proximal portion is about 3% of the overall length of        the rib portion;    -   rib intermediate portion has a circumferential width in the        range of from about 0.0005 to about 0.0100 inches;    -   rib intermediate portion has a circumferential width in the        range of from about 0.0011 to about 0.0062 inches;    -   rib intermediate portion has a circumferential width in the        range of from about 0.0016 to about 0.0024 inches;    -   the rib intermediate portion is from about 25% to about 90% of        the overall length of the rib portion;    -   the rib intermediate portion is from about 60% to about 90% of        the overall length of the rib portion;    -   the rib intermediate portion is about 90% of the overall length        of the rib portion;    -   rib distal portion has a circumferential width in the range of        from about 0.0010 to about 0.0120 inches;    -   rib distal portion has a circumferential width in the range of        from about 0.0013 to about 0.0072 inches;    -   rib distal portion has a circumferential width in the range of        from about 0.0016 to about 0.0024 inches;    -   the rib distal portion is up to about 25% of the overall length        of the rib portion;    -   the rib distal portion is from about 4% to about 16% of the        overall length of the rib portion;    -   the rib distal portion is up to about 7% of the overall length        of the rib portion;    -   the rib proximal portion is configured to form a rib proximal        portion acute angle with respect to a longitudinal axis of the        endovascular prosthesis;    -   the rib proximal portion acute angle is in the range of from        about 15° to about 90°;    -   the rib proximal portion acute angle is in the range of from        about 35° to about 60°;    -   the rib proximal portion acute angle is about 45°;    -   the rib distal portion is configured to form a rib distal        portion angle with respect to a rib intermediate portion of the        endovascular prosthesis;    -   the rib distal portion angle is in the range of from about 0° to        about 120°;    -   the rib distal portion angle is in the range of from about 3° to        about 60°;    -   the rib distal portion angle is about 8°;    -   the rib intermediate portion is configured to form a rib        intermediate portion acute angle with respect to a longitudinal        axis of the endovascular prosthesis;    -   the rib intermediate portion acute angle is in the range of from        about 5° to about 140°;    -   the rib intermediate portion acute angle is in the range of from        about 22° to about 86°;    -   the rib intermediate portion acute angle is about 45°;    -   the rib intermediate portion comprises: (i) a rib intermediate        first portion connected to the rib proximal portion and        configured to form a rib intermediate first portion acute angle        with respect to a longitudinal axis of the endovascular        prosthesis, and (ii) a rib intermediate second portion connected        to the rib distal portion and configured to form a rib        intermediate second portion acute angle with respect to a        longitudinal axis of the endovascular prosthesis;    -   the rib intermediate first portion acute angle is less than the        rib intermediate second portion acute angle;    -   the rib intermediate first portion acute angle is in the range        of from about 5° to about 140°;    -   the rib intermediate first portion acute angle is in the range        of from about 22° to about 66°;    -   the rib intermediate first portion acute angle is about 30°;    -   the rib intermediate second portion acute angle is in the range        of from about 5° to about 140°;    -   the rib intermediate second portion acute angle is in the range        of from about 42° to about 86°;    -   the rib intermediate second portion acute angle is about 60°;    -   the rib intermediate first portion has a circumferential width        in the range of from about 0.0010 to about 0.0100 inches;    -   the rib intermediate first portion has a circumferential width        in the range of from about 0.0014 to about 0.0062 inches;    -   the rib intermediate first portion has a circumferential width        in the range of from about 0.0018 to about 0.0024 inches;    -   the rib intermediate first portion is from about 5% to about 25%        of the overall length of the rib portion;    -   the rib intermediate first portion is from about 7% to about 17%        of the overall length of the rib portion;    -   the rib intermediate first portion is about 9% of the overall        length of the rib portion;    -   the rib intermediate second portion has a circumferential width        in the range of from about 0.0005 to about 0.0070 inches;    -   the rib intermediate second portion has a circumferential width        in the range of from about 0.0011 to about 0.0044 inches;    -   the rib intermediate second portion has a circumferential width        in the range of from about 0.0016 to about 0.0018 inches;    -   the rib intermediate second portion is from about 25% to about        90% of the overall length of the rib portion;    -   the rib intermediate second portion is from about 53% to about        85% of the overall length of the rib portion;    -   the rib intermediate second portion is about 81% of the overall        length of the rib portion;    -   in two dimensions, the rib distal portion of each rib portion is        directed away from the first expandable portion;    -   in two dimensions, the rib distal portion of each rib portion is        directed toward the first expandable portion;    -   in two dimensions, each rib portion is linear;    -   in two dimensions, each rib portion is curvilinear;    -   in two dimensions, each rib portion is curved;    -   in two dimensions, each rib portion comprises at least two        sub-portions each sub-portion form a different angle with        respect to a longitudinal axis of the endovascular prosthesis;    -   a pair of longitudinally adjacent rib portions are spaced at a        connection point to the spine portion at a distance ranging from        about 0.0254 mm to about 10 mm;    -   a pair of longitudinally adjacent rib portions are spaced at a        connection point to the spine portion at a distance ranging from        about 0.0254 mm to about 5 mm;    -   a pair of longitudinally adjacent rib portions are spaced at a        connection point to the spine portion at a distance ranging from        about 0.1400 mm to about 3 mm;    -   a pair of longitudinally adjacent rib portions are spaced at a        connection point to the spine portion at a distance ranging from        about 0.1400 mm to about 1 mm;    -   a pair of longitudinally adjacent rib portions are spaced at a        connection point to the spine portion at a distance ranging from        about 0.1400 mm to about 0.8 mm;    -   a pair of longitudinally adjacent rib portions are spaced at a        connection point to the spine portion at a distance ranging from        about 0.1400 mm to about 0.6 mm;    -   a pair of longitudinally adjacent rib portions are spaced at a        connection point to the spine portion at a distance of about        0.254 mm;    -   in two dimensions, the at least one spine portion and the        plurality of rib portions attached to the spine portion combine        to occupy less than about 75% of a surface area of the        retractable leaf portion;    -   in two dimensions, the at least one spine portion and the        plurality of rib portions attached to the spine portion combine        to occupy from about 5% to about 75% of a surface area of the        retractable leaf portion;    -   in two dimensions, the at least one spine portion and the        plurality of rib portions attached to the spine portion combine        to occupy from about 5% to about 65% of a surface area of the        retractable leaf portion;    -   in two dimensions, the at least one spine portion and the        plurality of rib portions attached to the spine portion combine        to occupy from about 10% to about 50% of a surface area of the        retractable leaf portion;    -   in two dimensions, the at least one spine portion and the        plurality of rib portions attached to the spine portion combine        to occupy from about 15% to about 40% of a surface area of the        retractable leaf portion;    -   in two dimensions, the at least one spine portion and the        plurality of rib portions attached to the spine portion combine        to occupy less than about 10% of a surface area of the        retractable leaf portion;    -   in two dimensions, the at least one spine portion and the        plurality of rib portions attached to the spine portion combine        to occupy less than about 8% of a surface area of the        retractable leaf portion;    -   in two dimensions, the at least one spine portion and the        plurality of rib portions attached to the spine portion combine        to occupy less than about 5% of a surface area of the        retractable leaf portion;    -   in two dimensions, the at least one spine portion and the        plurality of rib portions attached to the spine portion combine        to occupy less than about 3% of a surface area of the        retractable leaf portion;    -   the retractable leaf portion further comprises a cover layer        connected to the plurality of rib portions;    -   the retractable leaf portion comprises less than 10        longitudinally spaced rib portions connected on one side of the        spine portion;    -   the retractable leaf portion comprises less than 8        longitudinally spaced rib portions connected on one side of the        spine portion;    -   the retractable leaf portion comprises less than 6        longitudinally spaced rib portions connected on one side of the        spine portion;    -   the retractable leaf portion contains only 3 longitudinally        spaced rib portions connected on one side of the spine portion;    -   the ratio of the perpendicular distance from the longitudinal        axis to the distal tip portion of the rib portion to 50% of the        circumference of the first expandable portion in the second,        expanded state is in the range of from about 1:4 to about 1:1;    -   in two dimensions, the ratio of the perpendicular distance from        the longitudinal axis to the distal tip portion of the rib        portion to 50% of the circumference of the first expandable        portion in the second, expanded state is in the range of from        about 1:2.5 to about 1:1.5;    -   in two dimensions, the ratio of the perpendicular distance from        the longitudinal axis to the distal tip portion of the rib        portion to 50% of the circumference of the first expandable        portion in the second, expanded state is about 5:9;    -   the at least one spine portion is curved about an axis        transverse to a longitudinal axis of the endovascular        prosthesis;    -   the at least one spine portion is curved about an axis        substantially orthogonal to a longitudinal axis of the        endovascular prosthesis;    -   the axis is opposed to the plurality of rib portions relative to        the at least one spine portion;    -   the at least one spine portion comprises a first radius of        curvature over the length of the at least one spine portion        about an axis transverse to a longitudinal axis of the        endovascular prosthesis;    -   the first radius of curvature is substantially constant from a        proximal portion of the at least one spine portion to a distal        portion of the at least one spine portion;    -   the first radius of curvature is variable from a proximal        portion of the at least one spine portion to a distal portion of        the at least one spine portion;    -   the first radius of curvature decreases from a proximal portion        of the at least one spine portion to a distal portion of the at        least one spine portion.    -   the retractable leaf portion comprises a second radius of        curvature over the length of the at least one spine portion        about a longitudinal axis of the endovascular prosthesis;    -   the second radius of curvature is substantially constant from a        proximal portion of the retractable portion to a distal portion        of the retractable portion;    -   the second radius of curvature is variable from a proximal        portion of the retractable leaf portion to a distal portion of        the retractable leaf portion;    -   the second radius of curvature increases from a proximal portion        of the retractable leaf portion to a distal portion of the        retractable leaf portion;    -   in an expanded configuration of the endovascular prosthesis, the        retractable leaf portion comprises an arc of curvature about a        longitudinal axis of the endovascular prosthesis in the range of        from about 90° to about 360°;    -   in an expanded configuration of the endovascular prosthesis, the        retractable leaf portion comprises an arc of curvature about a        longitudinal axis of the endovascular prosthesis in the range of        from about 120° to about 270°;    -   in an expanded configuration of the endovascular prosthesis, the        retractable leaf portion comprises an arc of curvature about a        longitudinal axis of the endovascular prosthesis in the range of        from about 150° to about 250°;    -   in an expanded configuration of the endovascular prosthesis, the        retractable leaf portion comprises an arc of curvature about a        longitudinal axis of the endovascular prosthesis in the range of        from about 175° to about 225°;    -   in an expanded configuration of the endovascular prosthesis, the        retractable leaf portion comprises an arc of curvature about a        longitudinal axis of the endovascular prosthesis of about 200°;    -   the first expandable portion has a diameter in the second,        expanded state in range of from about 2 mm to about 40 mm;    -   the first expandable portion has a diameter in the second,        expanded state in range of from about 2 mm to about 30 mm;    -   the first expandable portion has a diameter in the second,        expanded state in range of from about 2 mm to about 20 mm;    -   the first expandable portion has a diameter in the second,        expanded state in range of from about 2 mm to about 10 mm;    -   the first expandable portion has a diameter in the second,        expanded state in range of from about 2.5 mm to about 5 mm;    -   a single spine portion is connected to the first expandable        portion and a loop portion is connected to a distal portion of        the single spine portion;    -   a single spine portion is connected to the first expandable        portion and a split loop portion connected to a distal portion        of the single spine portion;    -   the loop portion comprises a radioopaque portion;    -   the endovascular prosthesis further comprises a second        expandable portion expandable from a first, unexpanded state to        a second, expanded state to urge the first expandable portion        against a vascular lumen;    -   the second expandable portion comprises a radioopaque portion;    -   the endovascular prosthesis is manufactured from a tubular        starting material;    -   the endovascular prosthesis is manufactured from a tubular        starting material on which a cutting technique has been applied;    -   the endovascular prosthesis is manufactured from a tubular        starting material on which a laser cutting technique has been        applied;    -   tubular wall has a radial thickness in the range of from about        0.0005 to about 0.0200 inches;    -   the tubular wall has a radial thickness in the range of from        about 0.0015 to about 0.0100 inches;    -   the tubular wall has a radial thickness of about 0.0025 inches;    -   the first expandable portion comprises a radioopaque portion;    -   the prosthesis is constructed from a self-expanding material;    -   the prosthesis is constructed from a shape memory alloy;    -   the prosthesis is constructed from nitinol;    -   the prosthesis is constructed from a metallic material; and/or    -   the prosthesis is constructed from a polymer material.

In one of its aspects, the present invention relates to an endovascularprosthesis delivery device comprising a tubular member having a distalportion and a proximal portion, the distal portion having a poroussurface defined by a plurality of circumferential rings, adjacent pairsof circumferential rings being interconnected by at least onelongitudinal strut, the porous surface comprising a decreasing gradientof longitudinal strut circumferential width between longitudinal strutsconnected to opposed sides of a single circumferential ring in adirection from the proximal portion to the distal portion. Preferredembodiments of this endovascular prosthesis delivery device may includeany one or a combination of any two or more of any of the followingfeatures:

-   -   each circumferential ring comprises alternating peaks and        valleys;    -   the at least one longitudinal strut connects a first valley in a        first circumferential ring to a second valley in a second        circumferential ring adjacent to the first circumferential ring;    -   the at least one longitudinal strut connects to a mid-point of        the first valley;    -   the at least one longitudinal strut connects to a mid-point of        the second valley;    -   the at least one longitudinal strut connects to: (i) a mid-point        of the first valley, and (ii) a mid-point of the second valley;    -   the first circumferential ring and the second circumferential        ring each comprise at least one pair of alternating peaks and        valleys;    -   the first circumferential ring and the second circumferential        ring each comprise at least two pairs of alternating peaks and        valleys;    -   the endovascular prosthesis delivery device comprises a        longitudinal strut for each peak;    -   the endovascular prosthesis delivery device comprises a        longitudinal strut for each valley;    -   the endovascular prosthesis delivery device comprises a        longitudinal strut for each pair of alternating peaks and        valleys in first circumferential ring or the second        circumferential ring;    -   the first circumferential ring and the second circumferential        ring each comprise one pair of alternating peaks and valleys;    -   two longitudinal struts interconnect the first circumferential        ring and the second circumferential ring;    -   the plurality of circumferential rings comprises a first        circumferential ring, a second circumferential ring axially        spaced from the first circumferential ring and a third        circumferential ring axially spaced from the second        circumferential ring;    -   the first circumferential ring and the third circumferential        ring are spaced at a distance that is in the range from about        100% to about 300% of the diameter of the tubular member;    -   the first circumferential ring and the third circumferential        ring are spaced at a distance that is in the range from about        175% to about 225% of the diameter of the tubular member;    -   the first circumferential ring and the third circumferential        ring are spaced at a distance that is about 200% of the diameter        of the tubular member;    -   the porous surface has a proximal porous portion and a distal        porous portion disposed distally of the proximal porous portion;    -   the endovascular prosthesis delivery device comprises a first        longitudinal strut disposed in the distal porous portion and a        second longitudinal strut disposed in the proximal porous        portion, with the proviso that a first longitudinal strut        circumferential width of the first longitudinal strut is less        than a second longitudinal strut circumferential width of the        second longitudinal strut;    -   the first longitudinal strut circumferential width and the        second longitudinal strut circumferential width each are in the        range of from about 0.0010 in to about 0.0500 in;    -   the first longitudinal strut circumferential width and the        second longitudinal strut circumferential width each are in the        range of from about 0.0035 in to about 0.0300 in;    -   the first longitudinal strut circumferential width and the        second longitudinal strut circumferential width each are in the        range of from about 0.0045 in to about 0.0150 in;    -   the first longitudinal strut circumferential width is greater        than about 0.0010 in and the second longitudinal strut        circumferential width is less than about 0.0500 in;    -   the first longitudinal strut circumferential width is greater        than about 0.0035 in and the second longitudinal strut        circumferential width is less than about 0.0300 in;    -   the first longitudinal strut circumferential width is greater        than about 0.0045 in and the second longitudinal strut        circumferential width is less than about 0.0150 in;    -   the endovascular prosthesis delivery device comprises a first        circumferential ring disposed in the distal porous portion and a        second circumferential ring disposed in the proximal porous        surface, with the proviso that a first axial width of the first        circumferential ring is less than a second axial width of the        second circumferential ring;    -   the first axial width and the second axial width each are in the        range of from about 0.0010 in to about 0.0450 in;    -   the first axial width and the second axial width each are in the        range of from about 0.0040 in to about 0.0325 in;    -   the first axial width and the second axial width each are in the        range of from about 0.0050 in to about 0.0250 in;    -   the first axial width is greater than about 0.0010 in and the        second axial width is less than about 0.0450 in;    -   the first axial width is greater than about 0.0040 in and the        second axial width is less than about 0.0325 in;    -   the first axial width is greater than about 0.0050 in and the        second axial width is less than about 0.0250 in;    -   the endovascular prosthesis delivery device comprises a first        pair of adjacent circumferential rings disposed in the distal        porous portion and a second pair of circumferential rings        disposed in the proximal porous surface, with the proviso that a        first minimum distance between the first pair of adjacent        circumferential rings is greater than a second minimum distance        between the second pair of adjacent circumferential rings;    -   both of the first minimum distance and the second minimum        distance are in the range of from about 0.0010 in to about        0.0250 in;    -   both of the first minimum distance and the second minimum        distance are in the range of from about 0.0025 in to about        0.0190 in;    -   both of the first minimum distance and the second minimum        distance are in the range of from about 0.0040 in to about        0.0150 in;    -   the first minimum distance is less than about 0.0250 in and the        second minimum distance is greater than about 0.0010 in;    -   the first minimum distance is less than about 0.0190 in and the        second minimum distance is greater than about 0.0025 in;    -   the first minimum distance is less than about 0.0150 in and the        second minimum distance is greater than about 0.0040 in;    -   the endovascular prosthesis delivery device comprises a first        pair of adjacent circumferential rings disposed in the distal        porous portion and a second pair of circumferential rings        disposed in the proximal porous surface, with the proviso that a        first maximum distance between the first pair of adjacent        circumferential rings is greater than a second maximum distance        between the second pair of adjacent circumferential rings;    -   both of the first maximum distance and the second maximum        distance are in the range of from about 0.0050 in to about        0.0400 in;    -   both of the first maximum distance and the second maximum        distance are in the range of from about 0.0075 in to about        0.0365 in;    -   both of the first maximum distance and the second maximum        distance are in the range of from about 0.0090 in to about        0.0330 in;    -   the first minimum distance is less than about 0.0400 in and the        second minimum distance is greater than about 0.0050 in;    -   the first minimum distance is less than about 0.0365 in and the        second minimum distance is greater than about 0.0075 in;    -   the first minimum distance is less than about 0.0330 in and the        second minimum distance is greater than about 0.0090 in;    -   the endovascular prosthesis delivery device further comprises an        endovascular prosthesis connection portion attached to the        distal portion;    -   the endovascular prosthesis connection portion comprises at        least one elongate section comprising an intermediate section        and a distal section for connection to the endovascular        prosthesis;    -   at least one of the intermediate section and the distal section        are angled with respect to a longitudinal axis of the        endovascular prosthesis delivery device;    -   both of the intermediate section and the distal section are        angled with respect to a longitudinal axis of the endovascular        prosthesis delivery device;    -   the intermediate section and the distal section are angled with        respect to one another;    -   the endovascular prosthesis connection portion comprises a pair        of elongate sections comprising a first elongate section and a        second elongate section;    -   the first elongate section comprises an endovascular prosthesis        first attachment portion disposed at a distal end thereof;    -   the endovascular prosthesis first attachment portion comprises a        first half of a first male-female connection system for        receiving a second half of the first male-female connection        system disposed on an endovascular prosthesis;    -   the first half of the first male-female connection system        comprises a first male portion;    -   the second half of the first male-female connection system        comprises a first female portion;    -   the first half of the first male-female connection system        comprises a first female portion;    -   the second half of the first male-female connection system        comprises a first male portion;    -   the first half of the first male-female connection is configured        to receive a first endovascular prosthesis detachment member;    -   the second half of the first male-female connection is        configured to receive a first endovascular prosthesis detachment        member;    -   the first half and the second half of the first male-female        connection are configured to receive a first endovascular        prosthesis detachment member;    -   the first endovascular prosthesis detachment member comprises a        first wire member;    -   the second elongate section comprises an endovascular prosthesis        second attachment portion disposed at a distal end thereof;    -   the endovascular prosthesis second attachment portion comprises        a first half of a second male-female connection system for        receiving a second half of the second male-female connection        system disposed on an endovascular prosthesis;    -   the first half of the second male-female connection system        comprises a second male portion;    -   the second half of the second male-female connection system        comprises a second female portion;    -   the first half of the second male-female connection system        comprises a second female portion;    -   the second half of the second male-female connection system        comprises a second male portion;    -   the first half of the second male-female connection is        configured to receive a second endovascular prosthesis        detachment member;    -   the second half of the second male-female connection is        configured to receive a second endovascular prosthesis        detachment member;    -   the first half and the second half of the second male-female        connection are configured to receive a second endovascular        prosthesis detachment member;    -   the endovascular prosthesis detachment member comprises a wire        member;    -   the first elongate portion has a greater longitudinal length        than the second elongate portion;    -   the second elongate portion has a greater longitudinal length        than the first elongate portion; and/or    -   the first elongate portion and the second elongate portion have        a substantially equal longitudinal length.

With reference to FIGS. 1-2, there is illustrated an endovascularprosthesis 100. Endovascular prosthesis 100 comprises an expandableportion 105, a leaf portion 110 and a loop portion 115. Expandableportion 105 comprises a pair of undulating circumferential rings 106,107that are interconnected to one another by a pair of longitudinal struts108,109.

Leaf portion 110 comprises a spine portion 111 to which is connected afirst row of rib portions 112 on one side thereof and a second row ofrib portions 113 on an opposed side thereof. As can be seen, spineportion 111 comprises an undulating configuration (see also FIG. 1 a foran enlarged view of this feature). Individual ribs in each of rows112,113 are connected to the peaks of the undulating pattern formed byspine portion 111. This results in the connection points of individualrib portions in rows 112,113 being longitudinally offset with respect toone another.

The specifications for each rib portion in rows 112 and 113 arepreferred to be those mentioned above. Loop portion 115 comprises asingle loop portion 116, the function of which will be described in moredetail below.

Endovascular prosthesis 100 further comprises a series of radiopaquemarkers 120 disposed at various positions on prosthesis 100.

Expansible portion 105 comprises a pair of loop portions 122,124 forconnection to a delivery system (discussed below).

With reference to FIG. 1 a, there is illustrated an enlarged view of aportion of endovascular device 100. The following is a concordance ofterms used in FIG. 1 a (while the terms are illustrated with referenceto endovascular device 100, the also apply to endovascular devices 200,300, 400, 500 and 600 described in more detail hereinbelow) andelsewhere in this specification:

A root angle rib proximal portion acute angle B lead in angle ribintermediate first portion acute angle C rib angle rib intermediatesecond portion acute angle D tip angle rib distal portion acute angle Wroot width rib proximal portion X lead in width rib intermediate firstportion Y rib width rib intermediate second portion Z tip width ribdistal portion

With reference to FIG. 3, endovascular prosthesis 100 is connected to adelivery device 130. The details of delivery device 130 will bediscussed in further detail below. For present purposes, delivery device130 comprises at its distal end a pair of arms 135 (only one arm isshown in FIG. 3). Each arm 135 of delivery device 130 is connected toloop portion 122 or 124 of expansible portion 105 as shown in FIG. 3. Adelivery catheter 140 covers delivery device 130.

With reference to FIG. 4, further details are provided on connection ofdelivery device 130 to endovascular prosthesis 100 and deployment of thelatter.

Thus, delivery device 130 comprises a porous tube 132 at the distalportion of which may be found arms 135. One arm 135 is connected to loop122 of expansible portion 105 in a male-female arrangement while theother arm 135 is connected to loop portion 124 also in a male-femalerelationship. The connection between arms 135 and loop portions 122,124is maintained as shown in FIG. 4 by a pair of wires 137.

As shown in FIG. 4, endovascular prosthesis 100 is delivered to a bodypassageway 10 (i.e., an artery) having an aneurysm 15 with an aneurysmalopening 17. In the illustrated embodiment, endovascular prosthesis 100is a so-called self-expanding device. This means that when sheath 140 isretracted, endovascular prosthesis 100 will expand to its deployedstate.

In the illustrated embodiment, endovascular prosthesis 100 is positionedincorrectly with respect to aneurysm 15, particularly the aneurysmalopening 17. Specifically, the clinical goal is to have leaf portion 115covering aneurysmal opening 17 of aneurysm 15, ultimately leading toocclusion of aneurysm 15. As shown in FIG. 4, the clinical goal has notbeen achieved.

One of the specific advantages of the present invention generally andthe endovascular prosthesis specifically is that the prosthesis may berefracted into the sheath after it has been completely unsheathed andbefore it has been fully released and deployed. A device that isretracted and partially unsheathed is shown schematically in FIGS. 5 and6, respectively.

Thus, in FIG. 5 sheath 140 is extended to cover leaf portion 115 ofendovascular prosthesis 100. While, in the illustrated embodiment, loopportion 116 emanates from sheath 140 in FIG. 5, the entire device couldbe retracted into sheath 140, if desired. The orientation and design ofthe rib portions in leaf portion 115 facilitate retraction of leafportion 105 into sheath 140, for example, by allowing crisscrossing ofthe distal portions of respective rib portions in rows 112,113—this is aparticularly advantageous feature of the present endovascular prosthesisgenerally.

As shown in FIG. 5, re-sheathing of endovascular prosthesis 100 isachieved by relative movement between endovascular prosthesis 100 andsheath 140 in the direction of arrow A. When it is desired to unsheathendovascular prosthesis 100 (for the first time or otherwise), sheath140 is moved relative to endovascular prosthesis in the direction ofarrow B as shown in FIG. 6.

The ability to sheath, unsheath, re-sheath, etc. endovascular prosthesis100 as shown in FIGS. 5 and 6 is a distinct advantage of the presentendovascular prosthesis generally since it allows the clinician tooptimize the position of leaf portion 115 relative to aneurysmal opening17 of aneurysm 15, even after endovascular prosthesis 100 has beenpartially or fully unsheathed. Furthermore, the sheathing, unsheathing,re-sheathing, etc. . . . feature also allows the clinician to evaluatethe size (diameter and length) of the endovascular prosthesis relativeto the patient anatomy and if the sizing is not satisfactory theclinician can fully remove the endovascular prosthesis and exchange itfor a correctly sized device while maintaining the sheath in the patientat the target site.

The optimum position of endovascular prosthesis 100 is shown in FIG. 7wherein leaf portion 115 occludes aneurysmal opening 17 of aneurysm 15.The term “occlude” is used in a broad sense and generally means leafportion 115 covers aneurysmal opening 17 of aneurysm 15. While notwishing to be bound by any theory or particular mode of action, it isbelieved that this action of leaf portion 115 creates a pressure dropbetween aneurysm 15 and the parent vessel which leads ultimately toocclusion and healing. Single loop 116 of loop portion 115 serves toimprove apposition of leaf portion 110 in body passageway 10.

Once endovascular prosthesis 100 is in the correct position (this may beconfirmed by the clinical use of conventional radiography and observingthe position of radioopaque markers 120 relative to the target anatomy),endovascular prosthesis 100 is released from delivery device 130. Thisis achieved by retracting wires 137 (initial retraction is shown in FIG.7) which allows arms 135 of delivery device 130 to be released fromloops 122,124 of expansible portion 105 of endovascular prosthesis 100.Delivery device 130 and sheath 140 may then be withdrawn from thepatient. Leaving the correctly deployed endovascular prosthesis 100implanted as shown in FIG. 8.

With reference to FIGS. 9 and 10, there is illustrated an endovascularprosthesis 200. Endovascular prosthesis 200 is similar to endovascularprosthesis 100 illustrated in FIGS. 1-2 with the following exceptions:

-   -   single closed loop 116 in loop portion 115 of endovascular        prosthesis 100 has been replaced with a pair of split loop        portions 216 a,216 b;    -   the disposition of radioopaque markers 220 in endovascular        prosthesis 200 differs from the disposition of radioopaque        markers 120 in endovascular prosthesis 100;    -   the design of the individual ribs in leaf portion 210 of        endovascular prosthesis 200 has been slightly modified with        respect to the rib portions in leaf portion 110 of endovascular        prosthesis 100;    -   the rib portions in rows 212,213 of endovascular prosthesis 200        are more closely spaced than in endovascular prosthesis 100; and    -   loops 222 and 224 have been modified for attachment to the        delivery system.

The use of split loops 216 a,216 b provides improved apposition ofendovascular prosthesis 200. A single loop 116 as used in endovascularprosthesis 100 can protrude into the lumen of the artery if the singleloop is oversized relative to the size of the artery. The provision ofpair of split loops 216 a,216 b allows for overlap of each loop in agiven pair while avoiding bending into the lumen of the artery. Theaddition of radiopaque markers in this embodiment facilitatesvisualization by the clinician of the location of the extremities of theendovascular prosthesis 200. The provision of radiopaque markers 220 inexpansible portion 205 as illustrated facilitates visualization of oneend the end of prosthesis 200 while the provision of radiopaque markers220 in loop portion 215 as illustrated facilitates visualization of onethe other end of prosthesis 200.

Furthermore, having two markers near the spine of the leaf and depictingthe length of the occlusive length of leaf allows the clinician theability to evaluate whether or not the leaf length relative to theaneurismal opening 17 is adequate.

As can be seen, loop 222 comprises a pair of apertures 222 a,222 b.Similarly, loop 224 comprises a pair of apertures 224 a,224 b.

With reference to FIG. 11, endovascular prosthesis 200 is attached to adelivery device 230. As can be seen, delivery device 230 comprises aporous tube 232. A pair of arms 235 is provided at the distal end ofporous tube 232. FIG. 12( a) provides an enlarged view of region C ofFIG. 11. As can be seen, each arm 235 has a pair of apertures 235 a,235b. Aperture 235 a of arm 235 is aligned with aperture 222 a or 224 a ofloops 222 or 224, respectively. Similarly, aperture 235 b is alignedwith apertures 222 b or 224 b of loops 222 or 224, respectively. A loopwire 240 is then passed through these aligned loops to create a pair ofwire loops 241. Loop wire 240 may be a single wire for each of arms 235or it may be a pair of independent wires. A release wire 245 is then fedthrough loops 241. This can be seen more clearly with reference to FIG.12( b) which illustrates the arrangement of loop wire 240 and releasewire 245 without the detail of endovascular prosthesis 200 or deliverydevice 230. FIG. 12( c) shows the orientation of loop wire 240 on itsown.

Endovascular prosthesis 200 may be navigated to an aneurysm in the samemanner as described above with reference to endovascular prosthesis 100.Thus, endovascular prosthesis 200 also has a beneficial feature of beingable to be sheathed, unsheathed, re-sheathed, etc. as was the case forendovascular prosthesis 100.

When endovascular prosthesis 200 is positioned correctly. It can bedetached from delivery device 230 by sequentially retracting releasewire 245 and then retracting loop wire 240. As will be appreciated bythose of skill in the art, once release wire 245 is retracted, loops 241are free to be retracted from the apertures in loops 222,224 and theapertures in arms 235. Once loops 241 have been retracted in thismanner, endovascular prosthesis 200 will detach from arms 235 ofdelivery device 230.

With reference to FIGS. 13 and 14, there is illustrated an endovascularprosthesis 300. Endovascular prosthesis 300 is similar to endovascularprosthesis 200 described above with the exception that expansibleportion 305 has been modified. Specifically, expansible portion 305comprises an anchor spine 306 with a series of anchor ribs 307 disposedon opposite sides of anchor spine 306.

The other modification made to endovascular prosthesis 300 is theprovision of a single loop 322 comprising a pair of apertures 322 a,322b for connection to a delivery device.

The advantages of endovascular prosthesis 300 compared with endovascularprosthesis 200 include:

-   -   a single attachment connection between the prosthesis and the        delivery device compared to two connections for endovascular        prosthesis 200 (and endovascular prosthesis 100); and    -   addition of radioopaque markers near the rib tips near the        middle of the leaf portion, which are generally        circumferentially orthogonal to the markers close to the spine        portion of the leaf portion—these circumferentially orthogonal        markers help the clinician to evaluate the rotational position        of the device radiographically.

With particular reference to FIGS. 14 and 15, there is illustratedendovascular prosthesis device 300 connected to a delivery device 330having a porous tube 332. Disposed at the end of porous tube 332 is asingle arm 335. Arm 335 comprises a pair of apertures that, duringmanufacture, can be aligned with apertures 322 a,322 b of loop 322 ofendovascular prosthesis 300. After these apertures are aligned duringmanufacturing, a single loop/release wire 345 is fed through the alignedapertures to provide a pair of loops 341. The same loop/release wire 345is then fed back on itself through loops 341 as shown in FIGS. 15( a),(b), (c) and (d) which provide various details of how singleloop/release wire 345 is positioned. As shown, the end of singleloop/release wire 345 is permanently affixed to arm 335.

Endovascular prosthesis 300 may be delivered to a target aneurysm in thesame manner as described above with reference to endovascular prosthesis100 and endovascular prosthesis 200. Once endovascular prosthesis is inthe correct position, it may be detached from delivery device 330 byretracting loop/release wire 345. Initial retraction of loop/releasewire 345 removes it from loops 341. Continued retraction of loop/releasewire 345 removes loops 341 from aligned apertures in loop 322 ofendovascular prosthesis 300 and arm 335 of delivery device 330. At thispoint, delivery device 330 may be withdrawn leaving endovascularprosthesis 300 in place.

The endovascular prosthesis described above with reference to FIGS. 1-15is particularly well suited for occlusion of a so-called sidewallaneurysm. Occasionally, the target aneurysm is located at anintersection of a bifurcated artery such as the distal basilar arterydescribed above—such a target aneurysm is generally more difficult totreat than a sidewall aneurysm. For treatment of such a target aneurysm,it is preferred to further modify the endovascular prosthesis describedabove with reference to FIG. 115.

Thus, with reference to FIGS. 16-17, there is illustrated anendovascular prosthesis 400 that is particularly well suited fortreatment of an aneurysm located in a bifurcated artery. As can be seen,endovascular prosthesis 400 is similar to endovascular prosthesis 100described above with reference to FIGS. 1-2 with the followingmodifications:

-   -   expansible portion 405 (including circumferential rings 406,407        and struts 408,409) have been translated to the opposite end of        the spine 411 so that spine 411 is connected to a peak of        circumferential ring 406 (cf. spine 111 in endovascular        prosthesis 100 which is connected to a valley of circumferential        ring 106)—this feature facilitates delivery of endovascular        prosthesis 400 into either a straight or bifurcated body        passageway;    -   detachment loops 422,424 are located on opposed ends of        endovascular prosthesis 400 (cf. loops 122,124 located on        expansible portion 105 of endovascular prosthesis 100);    -   there is no loop portion in the proximal end of endovascular        prosthesis 400 as there is an endovascular prosthesis 100 (cf.        loop portion 115); and    -   a single attachment portion 424 is provided at a proximal end of        spine 411 of endovascular prosthesis 400.

With reference to FIGS. 18-21, there is illustrated delivery anddeployment of endovascular prosthesis 400 in a bifurcated artery 50. Ascan be seen, bifurcated artery 50 comprises an aneurysm 55 having ananeurysmal opening 57.

Of particular note in FIGS. 18-21 is the general manner in whichendovascular prosthesis is oriented during delivery and deployment.Specifically, when any of endovascular prosthesis 100,200,300 describedabove is delivered to a sidewall aneurysm, delivery is accomplished byorienting the expansible portion (105,205,305) such that it is proximalto the clinician whereas the loop portion (115,215,315) is orienteddistally with respect to the clinician thus exiting delivery catheter440 first. In contrast, when delivering endovascular prosthesis 400 tobifurcated artery 50, expansible portion 405 is oriented distally withrespect to the clinician whereas loop 424 (at the opposed end ofendovascular prosthesis with respect to expansible portion 405) isoriented proximally with respect to the clinician thus exiting deliverycatheter 440 last.

With reference to FIG. 18( a), a guidewire 66 is inserted and passedthrough a first branch 51 of bifurcated artery 50. Next, with referenceto FIG. 18( b), delivery catheter/sheath 440 is passed over guidewire 66into first branch 51 of bifurcated artery 50.

Next, with reference to FIG. 18( c), guidewire 66 is withdrawn fromfirst branch 51 of bifurcated artery 50. With reference to FIG. 18( d)endovascular prosthesis 400 attached to delivery device 430 is fedthrough delivery catheter/sheath 440 until endovascular prosthesis 400is positioned in first branch 51 of bifurcated artery 50.

With reference to FIG. 18( e) delivery catheter/sheath 440 is thereafterretracted: this results in initial deployment of expansible portion 405of endovascular prosthesis 400. If the physician is not satisfied withthis initial deployment of expansible portion 405 of endovascularprosthesis 400, he/she may re-sheath endovascular prosthesis 400 in anattempt to reposition it within first branch 51 of bifurcated artery 50.

Once the physician is satisfied with the initial deployment ofendovascular prosthesis 400, delivery catheter/sheath 440 is furtherretracted exposing the proximal portion of endovascular prosthesis400—see FIG. 18( f).

With reference to FIG. 19, delivery device 430 is further extended asshown in FIG. 19. This further extension naturally progresses into asecond branch 52 of bifurcated artery 50 due to the initial deploymentof endovascular prosthesis 400.

Once it has been determined that endovascular prosthesis 400 is in thecorrect position, delivery device 430 is detached from endovascularprosthesis 400 in the manner to be discussed below. This allows forwithdrawal of delivery catheter 440 and delivery device 430 resulting infinal deployment of endovascular prosthesis 400 as shown in FIG. 21. Inthis final deployed configuration, leaf portion 410 of endovascularprosthesis 400 occludes aneurysmal opening 57 of aneurysm 55.

With reference to FIG. 25, there is illustrated a delivery device 430for delivery of endovascular prosthesis 400. Delivery device 430comprises a porous surface 432 similar to the one described above withreference to endovascular prosthesis 100,200,300. Delivery device 430further comprises a first arm 435 having a square aperture 437 and asecond arm 442 having a cleat/buckle attachment 445. Cleat/buckleattachment 445 comprises a finger portion 447 having an aperture 448.Finger portion 447 is movable with respect to a protector portion 449 ofcleat/buckle attachment 445. Protector portion 449 of cleat/buckleattachment 445 protects against snagging of loop 424 during refractionof endovascular prosthesis 400.

With reference to FIGS. 22-24, there is illustrated further detail onattachment of arm 435 of delivery device 430 to loop portion 424 ofexpansible portion 405 of endovascular prosthesis 400. Thus, loopportion 424 is inserted in square aperture 437 and a wire 438 isinserted through loop portion 424 so as to secure loop portion 424 withrespect to square aperture 437—see FIG. 22. Once endovascular prosthesisis in the correct position and the clinician desires to detach deliverydevice 430 from endovascular prosthesis 400, wire 438 is retracted asshown in FIG. 23. This allows arm 435 to be separated from loop portion424 of endovascular prosthesis 400 as shown in FIG. 24.

With reference to FIGS. 26 and 27, there is illustrated further detailof attachment of attachment portion 422 of endovascular prosthesis 400to cleat/buckle attachment 445 of arm 442 of delivery device 430—forease of understanding the illustration has been styled outside thevasculature (cf. FIG. 20). Thus, finger portion 447 of cleat/buckleattachment 445 is inserted in a first aperture 426 of attachment portion422. A wire 428 is inserted through a second aperture 429 of attachmentportion 422 such that it also passes through aperture portion 448 offinger portion 447 of cleat buckle attachment 445—see FIG. 27. Thisarrangement serves to secure attachment portion 422 of endovascularprosthesis 400 with respect to cleat/buckle attachment 445 of deliverydevice 430.

When endovascular prosthesis 400 is in the correct position and theclinician wishes to detach endovascular prosthesis 400 from deliverydevice 430, the clinician retracts wire 428 from apertures 429,448. Thisallows finger portion 447 to be able to be retracted from aperture 426of attachment portion 422 thereby allowing detachment of that portion ofendovascular prosthesis 400 from delivery device 430.

At this point, delivery device 430 is detached from endovascularprosthesis 400 and the former may be fully refracted from the patientthrough delivery catheter/sheath 440 as shown in FIG. 20. The finaldeployment of endovascular prosthesis 400 is illustrated in FIG. 21.

With reference to FIGS. 28-35, there is illustrated an endovascularprosthesis 500 that is particularly well suited for treatment of ananeurysm located in a bifurcated artery. As can be seen, endovascularprosthesis 500 is similar to endovascular prosthesis 400 described abovewith reference to FIGS. 16-17 with the following general modifications:

-   -   the provision of arms 519;    -   the single radioopaque marker 420 in endovascular prosthesis 400        has been replaced by a trio of radioopaque markers 520 a,520        b,520 c;    -   the arrangement of radioopaque markers 520 in the rows 512,513        of rib portions has been altered;    -   single attachment portion 424 provided at the end of spine 411        of endovascular prosthesis 400 has been replaced by a pair of        arms 519 at the end of which is an attachment portion 524        comprising a pair of apertures 526,529.

A number of technical effects accrue from these modifications. Theadditional radiopaque markers provide the clinician with informationabout the location in the patient of the proximal and distal extremitiesof the endovascular prosthesis 500. In endovascular prosthesis 400, theradioopaque markers were disposed along the same side of the spineportion of the prosthesis. In contrast, in endovascular prosthesis 500,the radioopaque markers alternate along the spine portion and the mostproximal radioopaque marker is centred with the spine. Pair of arms 519in endovascular prosthesis 500 serve to urge the spine and rib portionstoward the aneurysmal opening and provide support to the spine and ribportions to urge them against the artery wall. Furthermore, pair of arms519 replace the function of second arm 442 of the delivery device usedin endovascular prosthesis 400.

With reference to FIGS. 30-35, there is illustrated attachment ofendovascular prosthesis 500 to a delivery device 530 which is similar todelivery device 430 described above. One difference is that first arm435 of delivery device 430 has been replaced with a first wire portion535 which is fed into loop portion 524 of expansible portion 505. A wire538 is fed through wire portion 535 as shown in FIG. 30 whichillustrates attachment of delivery device 530 to expansible portion 505.When it is desired to detach wire portion 535 form expansible portion505, wire 538 is retracted which allows wire portion 535 to disengagefrom loop portion 524 of expansible portion 505—see FIGS. 31 and 32.

With reference to FIG. 33, there is shown additional detail on deliverydevice 530. In essence, arms 435,442 used in endovascular prosthesis 400have been omitted. Specifically, arm 435 has been replaced with wireportion 535 and arm 442 has been omitted and replaced with a pair ofarms 519 in endovascular prosthesis 500—see FIG. 34. The function of arm442 is replaced by the presence of arms 519 in endovascular prosthesis500 with the added advantage that the curvature in arms 519 inendovascular prosthesis 500 aid in correct placement of endovascularprosthesis 500 in a bifurcated artery.

As shown, delivery device 530 comprises an attachment portion 542 whichis aligned with apertures 526,529 of arms 519 of endovascular prosthesis500 and secured as a unit by a loop wire 548 and a release wire 528. Asshown in FIG. 34, arms 519 of endovascular prosthesis 500 are alignedsuch that respective apertures 526,529 of each arm 519 are aligned. Loopwire 548 is passed through attachment portion 542 of delivery device530. A refraction wire 528 is passed through loop wire 548 as shown inFIG. 34 and also as shown in FIG. 35.

Endovascular prosthesis 500 may be delivered using delivery device 530in a manner similar to that described above in FIGS. 18-21 withreference to endovascular prosthesis 400.

With the reference to FIGS. 36 and 37, there is illustrated anendovascular prosthesis 600 that is particularly well suited fortreatment of aneurysm located in a bifurcated artery. As can be seen,endovascular prosthesis 600 is similar to endovascular prosthesis 500described above with reference to FIGS. 28 and 29 with the followinggeneral modifications:

-   -   pair of arms 519 in endovascular prosthesis 500 have been        replaced with a quartet of arms 619;    -   radioopaque markers 620 are arranged differently in endovascular        prosthesis 600 then radioopaque markers 520 a,520 b,520 c,520 in        endovascular prosthesis 500;    -   longitudinal strut 509 has been deleted thereby resulting in        element 606,607 being noncircumferential extending (they may be        regarded as so-called “split loops”); and    -   an element corresponding to attachment point 522 does not exist        on endovascular prosthesis 600, because the “expansible portion”        has been replaced with ribs or split loops and as such, no        longer requires an attachment point.

One of the principle advantages of endovascular prosthesis 600 is thatit may be delivered with a delivery device 630 which consists of asingle attachment to endovascular prosthesis 600. The provision of arms619 will improve urging of the spine portion and rib portions againstthe aneurysmal opening and against the artery wall. This is particularlyadvantageous since it allows for implantation of endovascular prosthesisin more varied anatomy than endovascular prosthesis 500. If endovascularprosthesis 600 is oversized relative to the target artery, arms 619 willremain against the artery wall and overlap each other, whereas inendovascular prosthesis 500, arms 519 may encroach into the lumen of theartery if the prosthesis were oversized. Similar advantage accrues withreference to elements 606 and 607. Finally, there are radioopaquemarkers disposed on both sides of the spine portion in endovascularprosthesis 600 compared to the alternating arrangement used inendovascular prosthesis 500—this provides a more detailed description ofthe leaf spine radiographically which allows for optimal positioningwith respect to the aneurysmal opening.

FIG. 37 illustrates connection of endovascular prosthesis 600 todelivery device 630. Specifically, attachment portion 622 ofendovascular prosthesis 600 is aligned with an attachment portion 632 ofdelivery device 630. While the details of connecting endovascularprosthesis 600 to delivery device 630 are not illustrated in FIG. 37, itis preferred to utilize a single loop/release wire as described abovewith reference to FIGS. 14 and 15 with the proviso that loops 341 areinverted when connecting endovascular prosthesis 600 to delivery device630.

With reference to FIGS. 38( i)-38(iii), there are illustrated variousviews of the distal portion of a endovascular prosthesis delivery device5. The illustrated distal portion has a porous surface. The remainder ofthe endovascular prosthesis delivery device (not shown for clarity) issubstantially non-porous.

As illustrated, there is an overall increase in porosity of the poroussurface of the endovascular prosthesis delivery device 5 moving from aproximal portion of the porous surface to the distal portion of theporous surface (left to right in FIGS. 38( i)-(iii)).

The present inventors have discovered that a combination of specificdimensions of the porous surface is particularly useful in conferring ahighly desirable balance between longitudinal flexibility and sufficientstructural integrity (re. torquing ability) to facilitate delivery of anendovascular prosthesis, particularly through tortuous vasculature.

Specifically, with particular reference to FIGS. 38( a) and 38(b), afunctional advantage accruing from a porous surface having thecombination of dimensions if it allows for bending of a longitudinalstrut 10 in the porous surface until the amount of bending allows foredges 20 of adjacent circumferential rings 25 to contact each other, atwhich point no further bending (strain) can be applied to longitudinalstrut 10. Consequently, there is a limit on the amount of strain thatcan be placed on longitudinal strut 10, thereby reducing the likelihoodof kinking, yield and/or failure of the material used to produce theporous surface of endovascular prosthesis delivery device 5.

With reference to FIGS. 38( a)-38(d), the dimensions for elements O, P,Q and R appearing in those drawings denote the concurrent transition forall of these elements from one end of the device to the other end:

Dimension (in.) O P Q R Preferred 0.0250-0.0010 0.0010-0.04500.0400-0.0050 0.0010-0.0500 More preferred 0.0190-0.0025 0.0040-0.03250.0365-0.0075 0.0035-0.0300 Most preferred 0.0150-0.0040 0.0050-0.02500.0330-0.0090 0.0045-0.0150

The number of transitions in elements O, P, Q and R is not particularlyrestricted. For example, in FIG. 38, there is a transition betweencircumferentially adjacent longitudinal struts (R) and longitudinallyadjacent circumferential rings P. However, the transition may achievedusing fewer steps—e.g., by having sub-sections with constant dimensionsfor O, P, Q and R. In this latter embodiment, the sub-sections may be ofsimilar or dissimilar longitudinal length. It is also possible to use acombination of one or more sub-sections with a series of individualtransitions.

The embodiment of the delivery device shown in FIG. 38 preferably has adiameter less than that of delivery catheter 140,440. Preferably, thedelivery device has a in the range of from about 0.015 to about 0.035inches, more preferably from about 0.020 to about 0.030 inches, mostpreferably 0.025 inch.

Endovascular prosthesis delivery device 5 is particularly well suitedfor delivery of the present endovascular prosthesis particularly when itis desired to deliver that prosthesis through torturous vasculature in apatient. Of course, it will be appreciated that endovascular prosthesisdelivery device 5 can be used to deliver other types of endovascularprostheses.

FIGS. 38-43 illustrate enlarged views of the distal portions of thevarious delivery devices described above identified with referencenumerals ending in “30”. The following is a concordance of theabove-described delivery devices and the above-described endovascularprosthesis preferably delivered by that delivery device:

Figure Delivery Device Endovascular Prosthesis 38 130 100 39(a)-(d) 230200 40(a)-(d) 330 300 41 430 400 42(a)-(c) 530 500 43(a)-(e) 630 600As can be seen in FIGS. 39-43, the porous, tubular portion of eachdelivery device is very similar but the distal section which is used toattach to the endovascular prosthesis is varied in each embodiment toaccommodate the specific type of endovascular prosthesis. In Figures,the distal section which is used to attach the endovascular prosthesisis heat set (e.g., in when the delivery device is constructed from ashape memory alloy such as nitinol) to facilitate delivery of theendovascular prosthesis—this is particularly advantageous when it isdesired to deliver the endovascular prosthesis to a bifurcated artery.The point is, a person of ordinary skill in the art, having in hand thepresent specification will understand that the specific nature of thedistal section which is used to attach to the endovascular prosthesis isnot specifically restricted. Further, a person of ordinary skill in theart will understand, having this specification in hand, that it may bepossible to mix and match certain illustrated embodiments of theendovascular prosthesis with certain illustrated embodiments of theendovascular prosthesis delivery device with or without minormodifications to one or both of these.

In a highly preferred embodiment, the present endovascular prosthesisdelivery device also is provided with a cover layer on the poroussurface thereof. The cover layer may be disposed on one or both of theinner and outer surfaces of the porous surface of the endovascularprosthesis delivery device. The provision of such a cover layer has beenfound to obviate or mitigate friction between the endovascularprosthesis delivery device and the interior of the deliver catheterconventionally used to deliver the endovascular prosthesis. Preferably,the cover layer is a made from a biocompatible polymer which can be anatural or a synthetic polymer. Non-limiting examples of a suitablepolymer may be selected from the group comprising polyurethanes,silicone materials, polyurethane/silicone combinations, rubbermaterials, woven and non-woven fabrics such as Dacron™, fluoropolymercompositions such as a polytetrafluoroethylene (PTFE) materials,expanded PTFE materials (ePTFE) such as and including Teflon™,Gore-Tex™, Softform™ Impra™ and the like. Preferably, the cover layerhas a thickness in the range of from about 0.00025 to about 0.00100inches, more preferably the cover layer has a thickness of about 0.00050inches.

The endovascular prosthesis of the present invention may furthercomprise a coating material thereon. The coating material can bedisposed continuously or discontinuously on the surface of theprosthesis. Further, the coating may be disposed on the interior and/orthe exterior surface(s) of the prosthesis. The coating material can beone or more of a biologically inert material (e.g., to reduce thethrombogenicity of the stent), a medicinal composition which leachesinto the wall of the body passageway after implantation (e.g., toprovide anticoagulant action, to deliver a pharmaceutical to the bodypassageway and the like), an expansible/swellable material (e.g., ahydrogel material) and the like.

Further, the present endovascular prosthesis may be provided with abiocompatible coating, in order of minimize adverse interaction with thewalls of the body vessel and/or with the liquid, usually blood, flowingthrough the vessel. A number of such coatings are known in the art. Thecoating is preferably a polymeric material, which is generally providedby applying to the stent a solution or dispersion of preformed polymerin a solvent and removing the solvent. Non-polymeric coating materialmay alternatively be used. Suitable coating materials, for instancepolymers, may be polytetrafluroethylene or silicone rubbers, orpolyurethanes which are known to be biocompatible. Preferably howeverthe polymer has zwitterionic pendant groups, generally ammoniumphosphate ester groups, for instance phosphorylcholine groups oranalogues thereof.

Examples of suitable polymers are described in International PublicationNumbers WO-A-93/16479 and WO-A-93/15775. Polymers described in thosedocuments are hemocompatible as well as generally biocompatible and, inaddition, are lubricious. When such coatings are used, it is preferredthat the surfaces of the endovascular prosthesis are completely coatedin order to minimize unfavourable interactions, for instance with blood,which might lead to thrombosis. This good coating can be achieved bysuitable selection of coating conditions, such as coating solutionviscosity, coating technique and/or solvent removal step.

The manner by which the present endovascular prosthesis is manufacturedis not particularly restricted. Preferably, the endovascular prosthesisis produced by laser cutting or chemical etching techniques applied to atubular starting material. Thus, the starting material could be a thintube of a metal or alloy (non-limiting examples include stainless steel,titanium, tantalum, nitinol, Elgiloy, NP35N, cobalt-chromium alloy andmixtures thereof) which would then have sections thereof cut out (bylaser cutting or chemical etching) to provide a prosthesis having apre-determined design. Alternatively, it is possible to cut the design(by laser cutting or chemical etching) of the prosthesis from a flatstarting material and thereafter roll the cut product into a tube andheat set in such a configuration or the edges of which could be weldedor otherwise secured together to form a tubular device.

In a particularly preferred embodiment, the present endovascularprosthesis is made from a suitable material which will expand when acertain temperature is reached. In this embodiment, the material may bea metal alloy (e.g., nitinol) capable of self-expansion at a temperatureof at least about 25° C., preferably in the range of from about 25° C.to about 35° C. In this preferred embodiment, it may be desired and evenpreferable to heat set the endovascular prosthesis to adopt a deployedconfiguration which has been optimized for the particular intendedanatomy—e.g., this is preferred for endovascular prosthesis 400,500,600described above.

While this invention has been described with reference to illustrativeembodiments and examples, the description is not intended to beconstrued in a limiting sense. Thus, various modifications of theillustrative embodiments, as well as other embodiments of the invention,will be apparent to persons skilled in the art upon reference to thisdescription. For example, the illustrated embodiments all utilize theleaf portion to act as a so-called flow diverter—i.e., once the deviceis implanted, the leaf portion diverts blood flow away from entering theaneurysmal opening. In cases where the aneurysmal opening is relativelylarge, it is possible to modify the leaf portion to act as a retentionmember—e.g., to retain one or more Guglielmi Detachable Coils in theaneurysm. In this modification, the spacing between adjacent ribportions would be increased a sufficient degree to allow delivery of oneor more Guglielmi Detachable Coils through the leaf portion afterimplantation of the endovascular prosthesis. The Guglielmi DetachableCoils would be less likely to “fall out” of the aneurysm when the leafportion of the present endovascular prosthesis is covering theaneurysmal opening. Further, while the illustrated embodiments depictattaching the endovascular prosthesis to the endovascular prosthesisdelivery device using release wire/loop wire systems with or withoutmale-female connection systems, other approaches may also be used—e.g.,electrolytic, thermal-mechanical, other mechanical and similarapproaches may be adopted. Further, while the illustrated embodimentsare focussed on treatment of a cerebral aneurysm, it is contemplatedthat the present endovascular prosthesis may be used to treat otherdiseases such as aortic disease (e.g., see the discussion of aorticdisease set out in International Publication Number WO 02/39924 [Erbelet al.]). In this modification, it may be appropriate to alter variousof the above-mentioned dimensions. For example, It is thereforecontemplated that the appended claims will cover any such modificationsor embodiments.

All publications, patents and patent applications referred to herein areincorporated by reference in their entirety to the same extent as ifeach individual publication, patent or patent application wasspecifically and individually indicated to be incorporated by referencein its entirety.

What is claimed is:
 1. An endovascular prosthesis comprising: a firstexpandable portion expandable from a first, unexpanded state to asecond, expanded state to urge the first expandable portion against avascular lumen; and a retractable leaf portion attached to the firstexpandable portion, the retractable leaf portion comprising a singlespine portion connected to the first expandable portion and a pluralityof rib portions attached to the spine portion, the plurality of ribportions comprising a pair of rows of rib portions connected to opposedsides of the single spine portion, longitudinally adjacent pairs of ribportions being free of interconnecting struts.